The present invention is directed to a method for reactivating a deactivated catalyst composition, and in particular to a method for reactivating a deactivated carbonylation catalyst composition, which is present in a post reaction mixture of a catalytic oxidative carbonylation reaction, and optionally recycling the re-activated catalyst composition in a subsequent oxidative carbonylation reaction without the need to individually isolate, purify, or reconstitute the original components of the catalyst composition.
A useful method for the production of aromatic carbonates includes the oxidative carbonylation of aromatic hydroxy compounds, with carbon monoxide and oxygen, which is typically catalyzed by a catalyst composition comprising a Group 8, 9 or 10 metal catalyst, various metal co-catalyst sources, a salt source, optionally an activating solvent, and optionally a base source. The lifetime of a typical carbonylation catalyst composition that can catalyze the production of aromatic carbonates, in an oxidative carbonylation reaction, is generally finite, thus resulting in a steady decrease in catalytic activity as the carbonylation reaction progresses. The decrease in catalytic activity is typically characterized by a steady decrease in the rate at which the desired aromatic carbonate is produced. Loss of catalytic activity during and after a carbonylation reaction can result from, but is not limited to, a change in reaction conditions (e.g., temperature, pressure), a decrease in the concentration of a reagent (e.g., oxygen), a change in the pH of the reaction mixture, an irreversible consumption of one or more components of the catalyst composition, and the build up of a particular side-product, which might act as a catalyst poison in the case of certain catalyst compositions.
The reactivation, and recycle, of a deactivated catalyst composition generally involves a removal step, a purification step, and a reconstitution step, wherein the individual components of the deactivated catalyst composition are first removed from a reaction mixture, purified, and then transformed into their original active forms before being recycled in a subsequent reaction. However, on a commercial scale these types of relatively complex processes are generally unattractive, because they result in the physical loss of unacceptable quantities of costly catalyst components. Consequently, a long felt yet unsatisfied need exists for a new and improved method for reactivating a deactivated catalyst composition previously used in an oxidative carbonylation reaction of an aromatic hydroxy compound, such that the re-activated catalyst composition can be re-used in a subsequent oxidative carbonylation reaction without the need to individually isolate, purify, and reconstitute the various components of the catalyst composition.
In one embodiment, the present invention is directed to a method for reactivating a deactivated carbonylation catalyst composition comprising a Group 8, 9 or 10 catalyst source, and a Group 14 metal first inorganic co-catalyst, which is present in a first liquid reaction mixture, said method comprising the following steps:
a first addition step, in which an aqueous solution comprising at least one protic acid source is added to said first liquid reaction mixture, forming a biphasic second liquid reaction mixture composed of an organic layer and an aqueous layer;
a mixing step, whereby the biphasic second liquid reaction mixture is effectively agitated for a predetermined amount of time, followed by a settling stage in order to repartition the mixture into the organic layer and the aqueous layer;
a first separation step, in which the organic layer of said biphasic second liquid reaction mixture is separated from said second liquid reaction mixture, to produce an aqueous third liquid reaction mixture;
an optional second separation step, in which any precipitate which was present in the denser phase of the second liquid reaction mixture is separated from the denser phase obtained after the first separation step;
an optional second addition step, in which any metal containing precipitate which was separated during the second separation step, is added to the third liquid reaction mixture to produce a fourth liquid reaction mixture; and
an evaporation step, wherein the volume of said fourth liquid reaction mixture is reduced by removing a predetermined amount of at least one component by evaporation at a predetermined temperature and pressure thus producing a concentrated fourth liquid reaction mixture;
wherein the carbonylation catalyst composition contained in the concentrated fourth liquid reaction mixture is more active, than the carbonylation catalyst composition contained in said first liquid reaction mixture, at carbonylating an aromatic hydroxy compound in a subsequent oxidative carbonylation reaction.
In another embodiment, the invention is directed to a method for reactivating a deactivated carbonylation catalyst composition comprising a Group 8, 9 or 10 catalyst source and a Group 14 metal first inorganic co-catalyst, which is present in a first liquid reaction mixture, said method comprising the following steps:
an optional first evaporation step, wherein the volume of the first liquid reaction mixture is reduced by removing a predetermined amount of at least one component by evaporation at a predetermined temperature and pressure to produce a concentrated first liquid reaction mixture;
a first addition step, in which an aqueous solution comprising at least one protic acid source is added to said first liquid reaction mixture, forming a biphasic second liquid reaction mixture composed of an organic layer and an aqueous layer;
a mixing step, whereby the biphasic second liquid reaction mixture is effectively agitated for a predetermined amount of time, followed by a settling stage in order to repartition the mixture into the organic layer and the aqueous layer;
a first separation step, in which the organic layer of said second liquid reaction mixture, is separated from said second liquid reaction mixture after a predetermined amount of time, to produce an aqueous third liquid reaction mixture;
an optional second separation step, in which any precipitate which was present in the denser phase of the second liquid reaction mixture is separated from the denser phase obtained after the first separation step;
an optional second evaporation step, wherein the volume of said aqueous third liquid reaction mixture is reduced by removing a predetermined amount of at least one component by evaporation at a predetermined temperature and pressure to produce a concentrated third liquid reaction mixture;
a second addition step, wherein a solution comprising at least one member selected from the group consisting of an activating solvent, an aromatic hydroxy compound, an aromatic carbonate, and any mixtures thereof is added to the third liquid reaction mixture, forming a fourth liquid reaction mixture;
a third evaporation step, wherein the volume of the fourth liquid reaction mixture is reduced by removing a predetermined amount of at least one component by evaporation at a predetermined temperature and pressure to produce a concentrated fourth liquid reaction mixture;
a third separation step, in which any components that precipitate from the concentrated fourth liquid reaction mixture after a predetermined amount of time are separated from the concentrated fourth liquid reaction mixture, therein producing a fifth liquid reaction mixture;
an third addition step, wherein at least one member selected from the group consisting of an aromatic hydroxy compound, an organic ligand source, an aromatic carbonate, a salt source, an activating solvent, a base source, and any mixtures thereof, is added to the fifth liquid reaction mixture to produce a sixth liquid reaction mixture; and
an optional fourth addition step, wherein any metal containing precipitate which was separated during the second separation step is added to the sixth liquid reaction mixture, therein producing an seventh liquid reaction mixture;
wherein the carbonylation catalyst composition contained in said seventh liquid reaction mixture is more active than the carbonylation catalyst composition contained is said first liquid reaction mixture at carbonylating an aromatic hydroxy compound in a subsequent oxidative carbonylation reaction.
In yet another embodiment, the present invention is directed to a method for reactivating a deactivated carbonylation catalyst composition comprising a Group 8, 9 or 10 catalyst source, and a Group 7 metal inorganic co-catalyst, which is present in a first liquid reaction mixture, said method comprising the following steps:
an addition step, in which an aqueous solution comprising at least one protic acid source is added to said first liquid reaction mixture, forming a biphasic second liquid reaction mixture composed of an organic layer and an aqueous layer;
a mixing step, whereby the biphasic second liquid reaction mixture is effectively agitated for a predetermined amount of time, followed by a settling stage in order to repartition the second liquid reaction mixture into the organic layer and the aqueous layer;
a separation step, in which the organic layer of said biphasic second liquid reaction mixture is separated from said second liquid reaction mixture, to produce an aqueous third liquid reaction mixture; and
an evaporation step, wherein the volume of said aqueous third liquid reaction mixture is reduced by removing a predetermined amount of at least one component by evaporation at a predetermined temperature and pressure thus producing a concentrated third liquid reaction mixture;
wherein the carbonylation catalyst composition contained in the concentrated third liquid reaction mixture is more active, than the carbonylation catalyst composition contained in said first liquid reaction mixture, at carbonylating an aromatic hydroxy compound in a subsequent oxidative carbonylation reaction.
In one embodiment, the present invention is directed to a method for reactivating a deactivated carbonylation catalyst composition previously used in a carbonylation reaction involving an aromatic hydroxy compound, carbon monoxide and oxygen, so that the re-activated catalyst composition is effective at carbonylating an aromatic hydroxy compound in a subsequent oxidative carbonylation reaction.
The method of the present invention is suitable for a typical carbonylation catalyst composition, comprising at least a Group 8, 9, or 10 catalyst source and a Group 14 metal inorganic co-catalyst source, which when active effectively catalyzes the production of aromatic carbonates via an oxidative carbonylation of aromatic hydroxy compounds with oxygen and carbon monoxide.
In the context of the present invention, the terms xe2x80x9cactivexe2x80x9d and xe2x80x9cactivatedxe2x80x9d, when used in reference to a catalyst composition, are meant to imply a condition in which the catalyst composition can catalyze the production of a desired aromatic carbonate at a rate which is greater than, or equal to, a predetermined reference rate. Herein, the rate of an oxidative carbonylation reaction is defined in terms of the catalyst xe2x80x9cturnover numberxe2x80x9d per hour (TON/h), which is a measure of moles of desired carbonate produced per mole of catalyst, during a predetermined amount of reaction time (e.g., one hour). For example, in one embodiment of the present invention, the catalyst TON=[(moles of diphenyl carbonate produced)/(moles of palladium)/hour]. In the context of the present invention, the term xe2x80x9cdeactivatedxe2x80x9d, when used in reference to a catalyst composition, connotes a formerly xe2x80x9cactivexe2x80x9d catalyst composition which in it""s current state, produces a desired aromatic carbonate at a rate which is below a predetermined reference rate. The term xe2x80x9creactivatedxe2x80x9d, when used in reference to a catalyst composition, is defined as the transformation of a formerly xe2x80x9cdeactivatedxe2x80x9d catalyst composition back to an xe2x80x9cactivexe2x80x9d catalytic state, in which the catalyst composition is once again capable of catalyzing the production of a desired aromatic carbonate in a subsequent oxidative carbonylation reaction, at a rate which is greater than, or equal to, a predetermined reference rate.
In the context of the present invention, the term xe2x80x9creaction conditionxe2x80x9d is meant to include, but is not limited to, reactor vessel pressure, reactor vessel temperature, reaction mixture temperature, agitation rate, gas flow rates (e.g., carbon monoxide flow rate and oxygen flow rate), gas mixture composition (e.g., ratio of carbon monoxide to oxygen), the pH of the reaction mixture, the weight % of various components of the liquid reaction mixture including, but not limited to, weight % of aromatic hydroxy compound, weight % of desired carbonate, weight % of water, and weight % of activating solvent.
In the context of the present invention, the term xe2x80x9creaction conditionxe2x80x9d is meant to include, but is not limited to, reactor vessel pressure, reaction temperature, agitation rate, gas flow rates (e.g., carbon monoxide flow rate and oxygen flow rate), gas mixture composition (e.g., the ratio of carbon monoxide to oxygen, or the presence of an additional gas source such as nitrogen), the pH of the reaction mixture, the weight % of various components of the liquid reaction mixture including, but not limited to, the weight % of an aromatic hydroxy compound, the weight % of a desired carbonate, the weight % of water, and the weight % of activating solvent.
In the context of the present invention, the term xe2x80x9cliquid reaction mixturexe2x80x9d is defined as a mixture of compounds, which are present predominantly in a liquid state at ambient room temperature and pressure (e.g., about 25xc2x0 C. and about 0.1 MPa). Liquid reaction mixtures can be homogeneous liquid mixtures composed of one of more phases (e.g., biphasic liquid reaction mixtures), or heterogeneous liquid-solid mixtures containing components that are present in the solid state (e.g., precipitates). In the present invention, a first liquid reaction mixture is typically a post-reaction mixture resulting from the carbonylation of an aromatic hydroxy compound using oxygen, carbon monoxide, and a catalyst composition. Herein, the individual constituents of a liquid reaction mixture are referred to as xe2x80x9ccomponentsxe2x80x9d. The components of a typical first liquid reaction mixture include, but are not limited to, the desired aromatic carbonate, byproducts of the carbonylation reaction which include, but are not limited to, water, aryl ethers, poly-aromatic hydroxy compounds, and aromatic carbonates other than the desired aromatic carbonate, dissolved reagent gases, soluble components of the catalyst composition, insoluble components of the catalyst composition which are present as precipitates, and unreacted aromatic hydroxy compound. Suitable types of aromatic hydroxy compounds include, but are not limited to, monocyclic aromatic compounds comprising at least one hydroxy group, and polycyclic aromatic compounds comprising at least one hydroxy group. Illustrative examples of suitable aromatic hydroxy compounds include, but are not limited to, phenol, alkylphenols, alkoxyphenols, bisphenols, biphenols, and salicylic acid derivates (e.g., methyl salicylate).
The carbonylation catalyst composition present in a typical liquid reaction mixture generally comprises a catalyst, which is a first metal source selected from a Group 8, 9 or 10 metal source. Typical Group 8, 9 or 10 metal sources include ruthenium sources, rhodium sources, palladium sources, osmium sources, iridium sources, platinum sources, and mixtures thereof. In one embodiment, about 1 ppm to about 10000 ppm of a Group 8, 9, or 10 metal source is present in the catalyst composition. In another embodiment, about 1 ppm to about 1000 ppm of a the Group 8, 9, or 10 metal source is present in the catalyst composition. In yet another embodiment of the present invention, about 1 ppm to about 100 ppm of a Group 8, 9, or 10 metal source is present in the catalyst composition. A typical Group 8, 9, or 10 metal source is a palladium source, including palladium compounds. As used herein, with respect to metal sources in general, the term xe2x80x9ccompoundxe2x80x9d includes inorganic, coordination and organometallic complex compounds. The compounds are typically neutral, cationic, or anionic, depending on the charges carried by the central metal and the coordinated ligands. Other common names for these compounds include complex ions (if electrically charged), Werner complexes, and coordination complexes. The Group 8, 9, or 10 metal source is typically present in the reaction mixture in a homogeneous form that is substantially soluble in the reaction mixture, or alternatively in a heterogeneous form which is substantially insoluble in the reaction mixture, including metal sources supported on substrates and polymer bound metal sources. Examples of suitable palladium sources include, but are not limited to, palladium sponge, palladium black, palladium deposited on carbon, palladium deposited on alumina, palladium deposited on silica, palladium halides, palladium nitrates, palladium carboxylates, palladium acetates, palladium salts of xcex2-diketones, palladium salts of xcex2-ketoesters, and palladium compounds containing at least one of the following ligands: carbon monoxide, amine, nitrite, nitrile, isonitrile, phosphine, phosphite, phosphate, alkoxide, alkyl, aryl, silyl or olefin.
Additional metal sources which are present in the catalyst compositions are typically referred to as inorganic co-catalysts. As used herein, the term xe2x80x9cinorganic co-catalystxe2x80x9d (IOCC) includes any catalyst component that contains a metal element, which is present in the catalyst composition in addition to the Group 8, 9 or 10 first metal source. Typically, one or two IOCC""s are present in the catalyst composition, and thus are present in the reaction mixture as a second metal source and a third metal source, respectively. Typical IOCC""s include, but are not limited to, compounds selected from the group consisting of Group 4 metal sources, Group 7 metal sources, Group 8 metal sources, Group 9 metal sources, Group 11 metal sources, Group 12 metal sources, Group 14 metal sources, Group 15 metal sources, Lanthanide sources, and mixtures thereof. Suitable forms of IOCC sources include, but are not limited to, elemental metals, metal oxides, and metal compounds in stable oxidation states. The IOCC compounds are typically neutral, cationic, or anionic, depending on the charges carried by the central atom and the coordinated ligands. The IOCC compounds are typically present in the reaction mixture in a homogeneous form that is substantially soluble in the reaction mixture, or alternatively in a heterogeneous form which is substantially insoluble in the reaction mixture, including metal sources supported on substrates and polymer bound metal sources. In one embodiment, about 1 equivalent to about 1000 equivalents of at least one IOCC source, versus the amount of a Group 8, 9, or 10 metal source, is present in the reaction mixture. In another embodiment, about 1 equivalent to about 500 equivalents of at least one IOCC source, versus the amount of a Group 8, 9, or 10 metal source, is present in the reaction mixture. In yet another embodiment of the present invention, about 1 equivalent to about 100 equivalents of at least one IOCC source, versus the amount of a Group 8, 9, or 10 metal source, is present in the reaction mixture. Examples of suitable IOCC sources for the present invention include, but are not limited to, lead sources, titanium sources, manganese sources, and copper sources. For example, in one embodiment a first IOCC is initially present in the carbonylation catalyst composition as lead(II) oxide. Other suitable lead sources include, but are not limited to, lead halide compounds (e.g., lead(II) bromide), lead alkoxy compounds (e.g., lead(II) methoxide), lead aryloxy compounds (e.g., lead(II) phenoxide), organometallic lead compounds having at least one lead-carbon bond, (e.g., alkyl lead compounds such as tetraethyllead(IV)), and lead compounds containing at least one of the following ligands: carbon monoxide, amine, nitrite, nitrile, isonitrile, cyanide, phosphine, phosphite, phosphate, alkoxide, alkyl, aryl, silyl or olefin. Mixtures of lead sources are also suitable. In another embodiment, the catalyst composition comprises a lead source in combination with a titanium source, originally charged as lead(II)oxide and titanyl(IV)oxide-bis-2,4-pentanedionate. In yet another embodiment the catalyst composition comprises a lead source in combination with a copper source, originally charged as lead(II)oxide and copper(II)-bis-2,4-pentanedionate. In yet another embodiment the catalyst composition comprises a manganese source, originally charged as manganese(II)bis-2,4-pentanedionate.
Typically, the carbonylation catalyst composition present in the liquid reaction mixture further comprises at least one salt source. Illustrative examples of suitable salt sources include, but are not limited to, alkali halides, alkaline-earth halides, guanidinium halides, and onium halides (e.g., ammonium halides, phosphonium halides, sulfonium halides), and compounds which contain an anion selected from the group consisting of carboxylates, acetates, and nitrates. Typical onium cations contain organic residues, which include C1-C6 alkyl, C6-C10 aryl, or alkyl-aryl combinations thereof. In one embodiment, about 1 equivalent to about 100000 equivalents of a salt source, versus the amount of a Group 8, 9, or 10 metal source, is present in the reaction mixture. In another embodiment, about 1 equivalent to about 10000 equivalents of a salt source, versus the amount of a Group 8, 9, or 10 metal source, is present in the reaction mixture. In yet another embodiment of the present invention, about 1 equivalent to about 5000 equivalents of a salt source, versus the amount of a Group 8, 9, or 10 metal source, is present in the reaction mixture.
When the salt source present in a carbonylation catalyst composition is an alkali halide salt source, or an alkaline-earth halide salt source, the catalyst composition typically further comprises an activating solvent. Generally, about 0.1% to about 50% by weight of activating solvent, based on the total weight of the liquid reaction mixture, is used. In another embodiment of the present invention, about 1% to about 20% by weight of activating solvent, based on the total weight of the reaction mixture is used. In yet another embodiment of the present invention, about 1% to about 10% by weight of activating solvent based on the total weight of the reaction mixture is used. For the present invention, suitable activating solvents include a polyether solvent (e.g. compounds containing two or more Cxe2x80x94Oxe2x80x94C linkages), and a nitrile solvent. Suitable polyether solvents include, aliphatic polyethers, and mixed aliphatic-aromatic polyethers. Examples of aliphatic polyethers include, but are not limited to, diethylene glycol dialkyl ethers such as diethylene glycol dimethyl ether (hereinafter xe2x80x9cdiglymexe2x80x9d), triethylene glycol dialkyl ethers such as triethylene glycol dimethyl ether (hereinafter xe2x80x9ctriglymexe2x80x9d), tetraethylene glycol dialkyl ethers such as tetraethylene glycol dimethyl ether (hereinafter xe2x80x9ctetraglymexe2x80x9d), polyethylene glycol dialkyl ethers such as polyethylene glycol dimethyl ether and crown ethers such as 12-crown-4 (1,4,7,10-tetraoxacyclododecane), 15-crown-5 (1,4,7,10,13-pentaoxacyclopentadecane) and 18-crown-6 (1,4,7,10,13,16-hexaoxacyclooctadecane). Illustrative examples of mixed aliphatic-aromatic polyethers include, but are not limited to, diethylene glycol diphenyl ether and benzo-18-crown-6. Mixtures of polyethers are also suitable. Suitable nitrile solvents include, but are not limited to, C2-C8 aliphatic or C7-C10 aromatic mononitriles or dinitriles. Illustrative mononitriles include, but are not limited to, acetonitrile, propionitrile, and benzonitrile. Illustrative dinitriles include, but are not limited to, succinonitrile, adiponitrile, and benzodinitrile. Mixtures of nitriles are also suitable.
In another embodiment of the present invention, the carbonylation catalyst composition further comprises at least one base source. Suitable types of base sources include, but are not limited to, basic oxides, hydroxides, mono-alkoxides, poly-alkoxides, monocyclic aryloxides, polycyclic aryloxides, and tertiary amines. Illustrative examples of suitable base sources include, but are not limited to, sodium hydroxide, lithium hydroxide, potassium hydroxide, tetraalkylammonium hydroxides (e.g. tetramethylammonium hydroxide, tetraethylammonium hydroxide, methyltributylammonium hydroxide, and tetrabutylammonium hydroxide) sodium phenoxide, lithium phenoxide, potassium phenoxide, tetraalkylammonium phenoxides (e.g. tetramethylammonium phenoxide, tetraethylammonium phenoxide, methyltributylammonium phenoxide, and tetrabutylammonium phenoxide), triethyl amine, and tributyl amine. In one embodiment, about 1 equivalent to about 10000 equivalents of a base source, versus the amount of a Group 8, 9, or 10 metal source, is present in the reaction mixture. In another embodiment, about 1 equivalent to about 1000 equivalents of a base source, versus the amount of a Group 8, 9, or 10 metal source, is present in the reaction mixture. In yet another embodiment of the present invention, about 1 equivalent to about 500 equivalents of a base source, versus the amount of a Group 8, 9, or 10 metal source, is present in the reaction mixture.
In the context of the present invention, the term xe2x80x9cevaporationxe2x80x9d is defined as the conversion of a component from the liquid state to the vapor state. The evaporation steps in the present method are included to reduce the volume of a particular liquid reaction mixture by concentrating that particular liquid reaction mixture by removing at least one volatile component, at a predetermined temperature and pressure, such as an aromatic hydroxy compound, a halogenated aromatic hydroxy compound, a hydrohalogenic acid, an activating solvent, or water, from a particular liquid reaction mixture. For example, in one embodiment, the initial step in the method is an optional evaporation step, which is included to reduce the volume of the first liquid reaction mixture.
One element of the present invention involves the addition of an xe2x80x9caqueous solutionxe2x80x9d comprising at least one xe2x80x9cprotic acid sourcexe2x80x9d to a first liquid reaction mixture. Herein, the term xe2x80x9caqueous solutionxe2x80x9d includes those solutions where water is present as a solvent. A xe2x80x9cprotic acid sourcexe2x80x9d is defined as a chemical species that can act as a source of protons (e.g., a Br xc3x6 nsted acid). Suitable examples of protic acid sources includes, but are not limited to, hydrohalogenic acids (e.g., hydrobromic acid, hydrochloric acid, and hydroiodic acid), sulfuric acid, nitric acid, and carboxylic acids. In one embodiment of the present invention, the aqueous solution consists of an aqueous hydrobromic acid solution where the hydrobromic acid is present at about 1 weight % (wt %) to about 48 wt %, based on the total weight of the solution. In another embodiment, the aqueous solution consists of an aqueous hydrobromic acid solution where the hydrobromic acid is present at about 11 wt % to about 20 wt %, based on the total weight of the solution. In yet another embodiment, the aqueous solution consists of an aqueous hydrobromic acid solution where the hydrobromic acid is present at about 1 wt % to about 10 wt %, based on the total weight of the solution. Addition of the aqueous solution to a primarily organic first liquid reaction mixture produces a biphasic second liquid reaction mixture with an organic phase and an aqueous phase, and can cause the formation of a lead containing precipitate, especially at lower concentrations of hydrobromic acid (e.g., about 3 weight %). The addition can be performed using equipment known to those skilled in the art including, but not limited to, a solvent extraction column, a mixer-settler vessel, and combinations thereof. Suitable temperatures for the addition are between about 60xc2x0 C. and about 140xc2x0 C. In one embodiment, the temperature of the addition is about 85xc2x0 C. Upon addition of the aqueous solution to the first liquid reaction mixture, the metal containing components, the salt source, and the cationic component of base source present in the catalyst composition will typically migrate from the organic phase to the aqueous phase. Depending on the components of a particular catalyst composition, a mixing step can be repeated multiple times in order to maximize the extraction of the water-soluble components of the carbonylation catalyst composition from the organic phase into the aqueous phase. Stirring, agitating, shaking, or inverting the biphasic second liquid reaction mixture can be used to obtain suitable mixing of the organic and aqueous phases. Effective phase separation of the second liquid reaction mixture is influenced by the temperature of the liquid reaction mixture, which is selected based on the specific composition of the liquid reaction mixture. Suitable temperatures for the phase separation of the second liquid reaction mixture are between about 60xc2x0 C. and about 140xc2x0 C. In one embodiment, the temperature of the second liquid reaction mixture during phase separation is about 85xc2x0 C.
Once effective phase separation has occurred, precipitate that may be present in the biphasic second liquid reaction mixture is typically separated in a first separation step. In the context of the present invention, the term xe2x80x9cseparationxe2x80x9d is defined as the isolation of at least one component of a liquid reaction mixture from the remaining components of the liquid reaction mixture. Herein, decanting, filtering, centrifuging, evaporating, or any combinations thereof can be used to achieve effective separation of a given component from a liquid reaction mixture. In the context of the present invention, the term separation also includes the division of the biphasic liquid reaction mixture into a separate organic phase liquid reaction mixture, and an aqueous phase liquid reaction mixture. When hydrobromic acid is the protic acid source in the aqueous solution that is added to the first liquid reaction mixture in the first addition step, typically a lead containing precipitate will form as a result of a reaction between the bromide ion and the lead source, leading to lead compounds such as lead(II) bromide which typically have low solubility constants (e.g., Ksp) in aqueous and organic solutions. The lead containing precipitate that is separated in this first separation step is typically combined with the other components of the catalyst composition at a later point in the method.
In one embodiment, an evaporation step is performed on the fourth liquid reaction mixture in order to reduce its volume, by removing a predetermined amount of water, to produce a concentrated fourth liquid reaction mixture which can either be returned to a subsequent carbonylation reaction to effectively catalyze the carbonylation or an aromatic hydroxy compound, or in an alternative embodiment, can be subjected to further steps before being returned to a subsequent carbonylation reaction. In one embodiment, a second addition step is made to the concentrated fourth liquid reaction mixture, in which a solution comprising an activating solvent is added to the fourth liquid reaction mixture to yield a fifth liquid reaction mixture. The fifth liquid reaction mixture is then subjected to a further evaporation step in order to reduce its volume by removing at least one volatile component. This evaporation step is followed by a third addition step, where additional components, such as a base source, are added to the fifth liquid reaction mixture to yield a sixth liquid reaction mixture. Typically the sixth liquid reaction mixture will contain a precipitate, which is removed by filtration, to produce a seventh liquid reaction mixture. Finally, the precipitate which was separated from the second liquid reaction mixture in a prior separation step, is combined along with the seventh liquid reaction mixture, thus forming an eighth liquid reaction mixture which comprises the reactivated catalyst composition which can to be returned to a subsequent carbonylation reaction to effectively catalyze the carbonylation or an aromatic hydroxy compound.
The following prophetic example is included to provide additional guidance to those skilled in the art at practicing the claimed invention. The prophetic example provided describes the manner by which one embodiment of the present method could be practiced by a person skilled in the art. Accordingly, the following prophetic example is not intended to limit the invention, as defined in the appended claims, in any manner.